Please refer to FIG. 1, which is a circuit block diagram schematically illustrating a lighting device according to prior art. The color temperature of the lighting device 1 is adjustable and controllable. The lighting device 1 includes a switch element 11, a driving and control device 12 and a light-emitting source 13. The driving and control device 12 includes a bridge current rectifying unit 121, a driving circuit 122 and a counting and control unit 123. The light-emitting source 13 includes a first light emitting diode (LED) unit 131 emitting a light of a first color temperature and a second light emitting diode (LED) unit 132 emitting a light of a second color temperature. The switch element 11, for example, can be mounted on the wall, while the driving and control device 12 and the light-emitting source 13 can be disposed in a light body 14.
The switch element 11 is coupled to a power source 9, e.g. mains electricity, and the bridge current rectifying unit 121. The bridge current rectifying unit 121 converts the alternating current into direct current. The counting and control unit 123 is electrically connected to the bridge current rectifying unit 121, the driving circuit 122 and the light-emitting source 13, counting a switching number of the switch element 11, which is turned on for receiving the direct current from the light-emitting source 13, and outputting an enable signal accordingly. The driving circuit 122 drives the first LED unit 131 to emit the light of the first color temperature and/or drives the second LED unit 132 to emit the light of the second color temperature. The details of the operational principle are disclosed in Taiwanese Patent Publication No. M392923, and are not to be redundantly described herein.
Unfortunately, it is found that the above-described architecture could not be applied to a lighting device with more than one light body due to the synchronous control problem.
For explanation in more detail, please refer to FIG. 2, which is a circuit block diagram schematically illustrating a light device with two light bodies 14 and 24. Similar to the lighting device shown in FIG. 1, respective light-emitting sources 13 and 23 of the light bodies 14 and 24 emit light of corresponding color temperatures according to the switching number of the switch element 11. However, since the electronic elements, e.g. capacitors, included in the two lighting bodies for the same functions may still differ in specifications or suffer from manufacturing deviations, the time taken for alternating current to enter the lighting body 14, be converted into direct current by the bridge current rectifying unit 121 and trigger the counting and control unit 123 to count and the time taken for alternating current to enter the lighting body 24, be converted into direct current by the bridge current rectifying unit 221 and trigger the counting and control unit 223 may be inconsistent. As a result, the light emission of the light-emitting source 13 of the light body 14 may desynchronize with the light emission of the light-emitting source 23 of the light body 24. For example, light could be emitted or extinguished at different time points for different lighting bodies.
Therefore, there is a need to improve such a light device.